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    <title>cl_khr_gl_event</title>
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        <a xmlns="http://www.w3.org/1999/xhtml" id="cl_khr_gl_event"></a>
        <h1>cl_khr_gl_event</h1>
        <p>
            Create a CL event object from a GL sync object.
        </p>
      </div>
      <div class="refsect2">
        <a id="synopsis"></a>
        <h3>
        </h3>
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#pragma OPENCL EXTENSION cl_khr_gl_event : enable
                        </td>
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            </tbody>
          </table>
        </div>
      </div>
      <div class="refsect1">
        <a id="description"></a>
        <h2>Description</h2>
        <p>
            This extension enables the funciton <a class="citerefentry" href="clCreateEventFromGLsyncKHR.html"><span class="citerefentry"><span class="refentrytitle">clCreateEventFromGLsyncKHR</span></span></a>. 
        </p>
        <p>
            This extension allows creating OpenCL event objects linked to OpenGL fence sync objects,
potentially improving efficiency of sharing images and buffers between the two APIs. The
companion <code class="function">GL_ARB_cl_event</code> OpenGL extension provides the complementary functionality of creating an OpenGL sync object from an OpenCL event object.
        </p>
        <p>
            This extension modifies the behavior of <a class="citerefentry" href="clEnqueueAcquireGLObjects.html"><span class="citerefentry"><span class="refentrytitle">clEnqueueAcquireGLObjects</span></span></a> 
            and <a class="citerefentry" href="clEnqueueReleaseGLObjects.html"><span class="citerefentry"><span class="refentrytitle">clEnqueueReleaseGLObjects</span></span></a> to implicitly guarantee synchronization with an OpenGL context bound in the same thread as the OpenCL context.
        </p>
        <p>
            If this extension is supported by an implementation, the string <code class="function">cl_khr_gl_event</code> will be present in the CL_PLATFORM_EXTENSIONS or CL_DEVICE_EXTENSIONS string described in the table of <code class="varname">param_name</code> values for <a class="citerefentry" href="clGetDeviceInfo.html"><span class="citerefentry"><span class="refentrytitle">clGetDeviceInfo</span></span></a>.
        </p>
        <p>
            If the <code class="function">cl_khr_gl_event</code> extension is supported, then the OpenCL implementation will ensure that any such pending OpenGL operations are complete for an OpenGL context bound to the same thread as the OpenCL context. This is referred to as <code class="varname">implicit synchronization</code>.
        </p>
        <p>
            If the <code class="function">cl_khr_gl_event</code> extension is supported and the OpenGL context in question supports
            fence sync objects, completion of OpenGL commands may also be determined by placing a GL fence command after 
            those commands using <code class="function">glFenceSync</code>, creating an event from the resulting GL sync object 
            using <a class="citerefentry" href="clCreateEventFromGLsyncKHR.html"><span class="citerefentry"><span class="refentrytitle">clCreateEventFromGLsyncKHR</span></span></a>, and determining completion 
            of that event object via <a class="citerefentry" href="clEnqueueAcquireGLObjects.html"><span class="citerefentry"><span class="refentrytitle">clEnqueueAcquireGLObjects</span></span></a>. This 
            method may be considerably more efficient than calling <code class="function">glFinish</code>, and is referred to as 
            <code class="varname">explicit synchronization</code>. Explicit synchronization is most useful when an OpenGL context 
            bound to another thread is accessing the memory objects.
        </p>
        <p>
            If the <code class="function">cl_khr_gl_event</code> extension is not supported, completion of OpenGL commands may be
            determined by issuing and waiting for completion of a <code class="function">glFinish</code> command on all OpenGL
            contexts with pending references to these objects. Some implementations may offer other efficient synchronization 
            methods. If such methods exist they will be described in platform-specific documentation.
            Note that no synchronization method other than <code class="function">glFinish</code> is portable between all OpenGL
            implementations and all OpenCL implementations. While this is the only way to ensure completion that is portable 
            to all platforms, <code class="function">glFinish</code> is an expensive operation and its use should be avoided if the
            <code class="function">cl_khr_gl_event</code> extension is supported on a platform.
        </p>
      </div>
      <div class="refsect1">
        <a id="notes"></a>
        <h2>Notes</h2>
        <p>
            When this extension is enabled, the following functions are also affected:
        </p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc; ">
            <li class="listitem" style="list-style-type: disc"><a class="citerefentry" href="clGetEventInfo.html"><span class="citerefentry"><span class="refentrytitle">clGetEventInfo</span></span></a>: Adds CL_COMMAND_GL_FENCE_SYNC_OBJECT_KHR as a possible return when <code class="varname">param_name</code> is CL_EVENT_COMMAND_TYPE.
            </li>
            <li class="listitem" style="list-style-type: disc"><a class="citerefentry" href="clWaitForEvents.html"><span class="citerefentry"><span class="refentrytitle">clWaitForEvents</span></span></a>: Event objects can also be used to reflect the status of an OpenGL sync object..
            </li>
          </ul>
        </div>
      </div>
      <div class="refsect1">
        <a id="specification"></a>
        <h2>Specification</h2>
        <p>
            <img src="pdficon_small1.gif" />
                                                 
            <a href="http://www.khronos.org/registry/cl/specs/opencl-1.1.pdf#page=327" target="OpenCL Spec">OpenCL Specification</a>
        </p>
      </div>
      <div class="refsect1">
        <a id="seealso"></a>
        <h2>Also see</h2>
        <p>
            <a class="citerefentry" href="EXTENSION.html"><span class="citerefentry"><span class="refentrytitle">EXTENSION</span></span></a>,
            <a class="citerefentry" href="clCreateEventFromGLsyncKHR.html"><span class="citerefentry"><span class="refentrytitle">clCreateEventFromGLsyncKHR</span></span></a>
        </p>
      </div>
      <div xmlns="" class="refsect3" lang="en" xml:lang="en"><a xmlns="http://www.w3.org/1999/xhtml" id="Copyright"></a><h4 xmlns="http://www.w3.org/1999/xhtml"></h4><img xmlns="http://www.w3.org/1999/xhtml" src="KhronosLogo.jpg" /><p xmlns="http://www.w3.org/1999/xhtml"></p>Copyright © 2007-2010 The Khronos Group Inc.
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"Materials"), to deal in the Materials without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
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